Table 5 DMD disability domains: item content and factor loadings where applicable^†

Fatigue impact

fatig1

My child got tired easily

ATN

0.81

fatig2

Being tired made it hard for my child to keep up with schoolwork

ATN

0.94

fatig3

My child had trouble starting things because he/she was too tired

ATN

0.95

fatig4

My child was so tired it was hard for him/her to pay attention

ATN

0.93

fatig6

My child was too tired to enjoy the things he/she likes to do

ATN

0.89

Strength impact

str1

My child was strong enough to open a heavy door

ATN

0.82

str2

My child was strong enough to pour a drink from a full pitcher or carton

ATN

0.97

str3

My child could open a jar by himself/herself

ATN

0.88

str4

My child was strong enough to raise his arms over his/her head

ATN

0.81

Upper extremity function

upper1

My child could button his/her shirt or pants

ATN

0.95

upper2

My child could open the rings in school binders

ATN

0.95

upper3

My child could pull a shirt on over his/her head without help

ATN

0.93

upper4

My child could put on his/her shoes without help

ATN

0.85

upper5

My child could use a key to unlock a door

ATN

0.94

Cognition function

cog1

Your child reacts slower than most people his/her age when he/she plays games

ATN

0.78

cog2

It is hard for your child to find his/her way to a place that he/she has visited several times before

ATN

0.85

cog3

It is hard for your child to pay attention to one thing for more than 5–10 min

ATN

0.86

cog4

Your child has to read things several times to understand them

ATN

0.88

cog6

It is hard for your child to understand pictures that show how to make something

ATN

0.91

cog7

It is hard for your child to add or subtract numbers in his/her head

ATN

0.84

cog8

Your child has to use written lists more often than other people his/her age so he/she will not forget things

ATN

0.90

cog9

It is hard for your child to find the right words to say what he/she means

ATN

0.87

cog10

Your child has trouble recalling the names of things

ATN

0.90

Negative affect (Bifactor model)

Anger

affect1

My child felt mad

ATN

0.74

Anxiety

affect2

My child felt nervous

ATN

0.81

Anxiety

affect3

My child felt scared

ATN

0.79

Anxiety

affect4

My child felt worried

ATN

0.87

Anxiety

affect5

It was hard for my child to relax

ATN

0.88

Depression

affect6

My child felt lonely

ATN

0.64

Depression

affect7

My child felt sad

ATN

0.81

Depression

affect8

My child didn't care about anything

ATN

0.69

Anger

stress1

Small things upset my child

ATN

0.71

Positive affect

peer2

My child felt a sense of belonging around his peers

ATN

0.66

pos1

My child felt happy

ATN

0.92

pos3

My child was in a good mood

ATN

0.94

pos4

My child felt calm

ATN

0.81

Mobility*

mob1

My child could get in and out of a car

ATN

NA

mob2

My child could do sports and exercise that other kids his/her age could do

ATN

NA

mob3

My child could get up from a regular toilet

ATN

NA

mob4

My child could keep up when he/she played with other kids

ATN

NA

mob5

My child has been physically able to do the activities he/she enjoys most

ATN

NA

mob6

My child could get up from the floor

AT

NA

mob7

My child could walk more than one block

AT

NA

mob8

My child could ride a bike

AT

NA

mob9

My child could walk across the room

AT

NA

mob10

My child could run a mile

A

NA

mob11

My child used a wheelchair to get around

ATN

NA

mob12

My child used a medical scooter to get around

ATN

NA

mob13

My child could move his/her legs

N

NA

Sleep-device symptoms*

sleep3

My child had muscle-cramping during the night

ATN

NA

sleep4

My child's leg braces were uncomfortable during the night

TN

NA

sleep5

My child was on a breathing machine at night (C-PAP or Bi-PAP)

ATN

NA

sleep6

My child had difficulty changing positions in his sleep

TN

NA